1. Field of the Invention
The present invention relates to an improved electric glass incense burner and a heat conducting device used therein.
2. Description of the Prior Art
An electric incense burner takes advantage of electric conduction to emit perfumed air. The air emitted is aromatic as well as clean. However, such electric incense burners are usually made of ceramic material, and thus has the following practiced disadvantages. (Please refer to FIG. 2).
1. The knob A2 on the lid A is made as a smooth column. It can inadvertently slip out of a user's hand when it is moist, and fall to the ground and be broken.
2. The lower part of the burner B has a bottom B1 which protrudes upward to create a cavity in which to fix a heating device. The fragility of the ceramic material makes the bottom part weakened. Moreover, a lip M extends under the bottom B1 to hold a clamping sheet L and a base C. A user must take care not to lock the base C and the conducting plate D too tightly. Otherwise, the bottom B1 is subject to cracking and the lip M can be broken. Moreover, the heat conducting effect of this burner is not optimal because the conducting plate D is fixedly attached to the central portion of the protruding bottom B1, thereby leaving the surrounding portion of the burner out of the contact with the heating device.
3. Because the incense burner B is produced by burning ceramic material, power may be wasted in construction.
The structure of a conventional heat conducting device, such as is shown in FIGS. 1 and 2, is constructed to have a metallic bottom plate E. a lower mica slice F. a middle mica slice G. and an upper mica slice H. etc. which are lapped and rivetted together. The middle mica slice G is wound with nickel and chromium wire G1. Both ends of the nickel and chromium wire G1 are connected by a pair of terminals I1 to conductors I which are connected to a switch and a plug. In such a heat conducting device, the upper mica slice H is fixed to the bottom B1 of the electric incense burner. The metallic bottom plate E is fixed to the bottom B1 of the electric incense burner B with a bolt J and a nut K and a clamping sheet L. The high heat produced in the nickel and chromium wires G1 after turning on the electricity is transmitted to the bottom B1 of the burner B through the upper mica slice H. However, such a conventional heat conducting device has the following defects due to its structure:
1) The metallic bottom plate E in the heat conducting device is conductive. Often, when the electric incense burner B is broken accidentally, or when water permeates into the bottom layer of the burner B, electric leakage can occur. Thus, users are subjected to the risk of electric shock.
2) The avoid losing heat efficiency, the heating power should be adapted to the length of the nickel and chromium wire, e.g., if 25 W heat energy ( 110 volts) is to be produced, the length of the nickel and chromium wire should be 500 mm. the nickel and chromium wire of the prior art heat conducting device is would by hand. Thereby allowing significant differences in lengths of the nickel and chromium wires. Inconsistent width of the turns of each nickel and chromium wire wound on the mica slice, or too large spaces between the wires, reduces the heating efficiency.
3) Resistance to high pressure of the metallic bottom plate E is inferior, and it will not pass the high pressure safety test of American UL (standard value is 1,500 v).